1  /* Copyright (C) 2002-2023 Free Software Foundation, Inc.
       2     Contributed by Zack Weinberg <zack@codesourcery.com>
       3  
       4  This file is part of GCC.
       5  
       6  GCC is free software; you can redistribute it and/or modify it under
       7  the terms of the GNU General Public License as published by the Free
       8  Software Foundation; either version 3, or (at your option) any later
       9  version.
      10  
      11  GCC is distributed in the hope that it will be useful, but WITHOUT ANY
      12  WARRANTY; without even the implied warranty of MERCHANTABILITY or
      13  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      14  for more details.
      15  
      16  Under Section 7 of GPL version 3, you are granted additional
      17  permissions described in the GCC Runtime Library Exception, version
      18  3.1, as published by the Free Software Foundation.
      19  
      20  You should have received a copy of the GNU General Public License and
      21  a copy of the GCC Runtime Library Exception along with this program;
      22  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      23  <http://www.gnu.org/licenses/>.  */
      24  
      25  /* Threads compatibility routines for libgcc2 for VxWorks.
      26  
      27     This file implements the init-once service exposed by gthr-vxworks.h.  */
      28  
      29  #include "tconfig.h"
      30  #include "tsystem.h"
      31  #include "gthr.h"
      32  
      33  #if defined(__GTHREADS)
      34  
      35  #include <vxWorks.h>
      36  #include <taskLib.h>
      37  
      38  #ifndef __RTP__
      39  # include <vxLib.h>
      40  # include <taskHookLib.h>
      41  #else /* __RTP__ */
      42  # include <errno.h>
      43  #endif /* __RTP__ */
      44  
      45  /* ----------------------------- Init-once ------------------------------- */
      46  
      47  static void
      48  __release (__gthread_once_t ** __guard)
      49  {
      50    (*__guard)->busy = 0;
      51  }
      52  
      53  int
      54  __gthread_once (__gthread_once_t * __guard, void (*__func) (void))
      55  {
      56    if (__guard->done)
      57      return 0;
      58  
      59    /* Busy-wait until we have exclusive access to the state.  Check if
      60       another thread managed to perform the init call in the interim.  */
      61    
      62    while (!__TAS(&__guard->busy))
      63      {
      64        if (__guard->done)
      65  	return 0;
      66        taskDelay (1);
      67      }
      68  
      69    if (!__guard->done)
      70      {
      71  #ifndef __USING_SJLJ_EXCEPTIONS__
      72        /* Setup a cleanup to release the guard when __func() throws an
      73  	 exception.  We cannot use this with SJLJ exceptions as
      74  	 Unwind_Register calls __gthread_once, leading to an infinite
      75  	 recursion.  */
      76        __attribute__ ((cleanup (__release)))
      77  	__gthread_once_t *__temp = __guard;
      78  #endif
      79  
      80        __func ();
      81        __guard->done = 1;
      82      }
      83  
      84    __release(&__guard);
      85    return 0;
      86  }
      87  
      88  #endif /* __GTHREADS */